aye, all the way forward is likely not the place you need it... To get my CG where I wanted it (nearly netural inverted barely positive normal flight) my batt sits with the end sticking out of the strap about 1/4", or in outher words, about 1.5" from the rearmost position...this probably won't be as far back as you need / want it, Because I have slightly heavier Landing gear than stock, and a bit under 3/4" of an inch added to the Trailing Edge of my wing.

hey guys, those who are flying the the battery not all the way front. are having the roll tendancy when loop? i think that with CG less nose heavy will stall less on a loop.

The plane is touchy with full elevator throws(37mm each direction) It will snap over when flying slow, and throwing a lot of elevator, this is the downside of the design that gives it the awesome spins and snap rolls. I added a flat carbon spar to the elevator(H-stab already has a spar in it), and 2 small peices slipped under each side of the plastic elevator joiner peice glued in that extend to the trailing edge, this takes a lot of the flex out of the elevator, and if anything, mine will roll to the left at slow speeds, this is normal due to motor torque, not right as most report with this plane. The CG does have an effect on stalling, it tends to stall at a higher speed, but much more gradually and forgiving with a nose heavy CG, with a neutral CG, it stalls a little slower, but more abuptly. I also have a gyro setup with low gain on the aileron channel, it keeps the wings locked into whatever orientation I want, it helps in the wind, and makes landings and takeoffs very easy. It is not turned up enough to really affect stalls, but does seem to cut down on some wing rock with harriers. In larger loops, the plane tracks perfectly straight, tight loops take a little right rudder which is normal to counteract torque, flips and the Extra's crappy version of a waterfall are not terribly crooked, a touch of right rudder, and moderate right aileron keep the wings level, maybe a bit more throw, but the same inputs that most every decent 3D plane I have flown require.

The further forward the CG is, the faster the stall speed. The plane is very sensitive to CG, while a CG that is forward can make it a bit more forgiving to fly, it does come at a cost, not only stalling, but up elevator trim is requred to fly level, flip it inverted and it will dive. You want to trim it till it dives or flies level the same rate upright or inverted at about 1/2-2/3 throttle, then move CG back in small increments, and it will get to a point where it flies pretty level upright or inverted, perhaps with just a touch of elevator to fly level, and perhaps more importantly upright and inverted downlines are straight, it won't dive deeper, or pull out without elevator input. On mine this perfect CG is about 2 7/8"-3" from the leaing edge. It will make the elevator more responsive, make knife edges more stable and require less rudder, and it will slow down a bit better, although it will still stall, any plane will. You need to fly the plane and control it from rolling on takeoff to rolling on landing, it is not as floaty as a 3D plane, or the PKZ warbird "trainers", for those you can cut the throttle, coast on in, and the plane practically lands itself. If you approach about 1/4 throttle from level flight and 6' high, and ease the plane down as you lower the throttle, flaring it gently just as the mains touch down it will land just fine.

If in doubt land faster, or add some throttle, better to land too fast than too slow, the gear can take it, on grass, bigger wheels without the wheel pants help, and you also will need to pull up elevator more and more as the plane settles on the ground, not enough to pick up the mains, but plenty to keep the tail planted, and keep it from nosing over, which is not really much of a problem with the plane. With aerobatic planes like this, throttle is your friend, and smooth inputs timed just right are the key to flying it proficiently.

The good and bad news is that the Extra is relatively docile and easy to land as far as aerobatic and 3D planes go, it only gets worse, and landing speeds will only get faster as you progress into more capable and challenging models.

You are absolutely right in saying that forward cg increases stall speed due to the increased download of the elevator position. However, the critical angle of attack remains the same, especially over the small speed differences we're talking about.

The point I was making about being easier to stall with an aft cg is related to the amount of elevator required to get to the critical angle of attack. Less elevator is required with the cg aft to achieve the critical angle of attack. I thought that would be a simpler way for someone to understand from the pilot's perspective since the change in stall speed is relatively small.

I added a flat carbon spar to the elevator(H-stab already has a spar in it), and 2 small pieces slipped under each side of the plastic elevator joiner piece glued in that extend to the trailing edge, this takes a lot of the flex out of the elevator

How did you put the spars in the elevator? Were they like the red and purple or like the blue and purple?

Images

How did you put the spars in the elevator? Were they like the red and purple or like the blue and purple?

One spar straight across, but on the underside close to the hinge point in the bevel. The other 2 are about 3" long each, pushed under the plastic joining peice, basically on the inside edges of the cutout for the rudder, then glued in place.

oopsie-tried to fly in 30mph winds just to see what it was like. Just like I predicted, takeoff ok, flight ok, landing gonna be a challenge, and it was. When the plane hit the ground, it was so far away from me i didnt see it hit. Minor damage, glue drying. I beleive i have enough skill that i could have done it, just dumb thumbed it

One spar straight across, but on the underside close to the hinge point in the bevel. The other 2 are about 3" long each, pushed under the plastic joining peice, basically on the inside edges of the cutout for the rudder, then glued in place.

Ahh ok. I get it now. There isn't much room between the plastic and the hinge, and being right on the hinge it doesn't do much, but once you tie it to the other ones on each side it links both sides together.

Images

wow-those pics turned out better than i thought they would-anyway,the first three pics are the popsicle stick frame with the Tx suspended in it. Pic 4 & 5 are the Tx suspended in the frame with 2 layers of some kinda funny blanket material. I dont know where it came from but its a thin layer of foam with "felt" on both sides. I had it layin around for years and didnt really use it so i canabalized it. RIP Mr. Blanket-Pic 6 is the finished product, with the "flap" down over the opening....hmmm...seems im m issing some pics...hang on